Heater



FIG. 1 is a perspective view of a heater showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and

FIG. 7 is a bottom view thereof; and,

FIG. 8 is an enlarged view of a portion 8 of the heater shown in FIG. 1.

The broken lines in the figures show portions of the heater that form no part of the claimed design. 

CLAIM The ornamental design for a heater, as shown and described. 